Ship&#39;s form



July 14, 1936. v. YOURKEVITCH SHIP S FORM Filed Mav 21, 1952 45 speed.

Patented 'July '14, 1936 um'rso .STATES PATENT orrlcs 2,047,451 smr'sroam Yourkcvitch, m, France Application May 21, 1932, Serial No. 612,701

' 1 Claim. (c1. 114-56) This invention relates to ships forms and isdirected more particularly to the modification of existing ships andmerchant ships in particular. The object of the invention-is to providea novel 5 method whereby the hulls of existing ships may be changed ormodified in order to increase their speed without necessitating increaseinthe power plant of the ship.

In my prior patent, No. 1,831,643, issued November 10, 1931, there isdisclosed ship construction adapted especially to be incorporated inships during the building thereof, whereby the maximum eiliciency of thepower plant in the development of speed may be insured especially in newships andwithin the original contemplated overall length thereof.

The primary object of the present invention from a more specificstandpoint consists in providing a novel and efllcient method wherebythe advantages 'of my former invention may be incorporated inshipsalready built by "modifying the hulls of such ships in' order toincrease their speed.

Hulls of ships, as heretofore made, may be classified generally intothree distinct classes, which are so named because of their particularcontour at the waterline, at the forward part 01 the ship. The firstclass and that which is almost universally found under-present practiceis the convex form wherein the fore part of the ship bulges outappreciably at the bow or stem in order to obtain maximum buoyancy inthis portion of the ship. The second form may be called a straight formbecause the sides 01' the hull extend substantially straight back fromthe stem of the hull .and impart almost a straight wedge shape to thefore part of the The third form may be termed a concave form. This fo'fmis almost unknown in merchant marine, 40 but has been attempted in somebattleship design, but without any degree 01 success.

I have'found by exhaustive experimentation and research that the concavehull form, if produced ina particular way will give maximum In the pastwhere this form has been attempted, the concave ship has been carriedout on a hit or miss theory, and almost invariably the result has beenthat a greater resistance has been set up to forward motion of the shipdue 50 tothe lack of any realization of the problems involved oi to-adefinite understanding of the factors confronting this type ofconstruction.

The present invention provides a method whereby ships already built andof which it is 55 desired to improve the performance as compared withusual practice, may be changed or modified in accordance with welldefined principles in order to give a marked increase in speed andwithout any question as to the results to be obtained.

I have found that this may be accomplished by rebuildinggthe fore partof the ship and slightly increasingi'the overall length of a shipsufficiently, however, to give a concave fore part at the waterli'nesoas to obtain a sectional area curve havin 10 also a concave curvature ofvariable radius and moreover characterized by a minimum radius ofcurvature at-a spot corresponding substantially to the abscissa of thecenter of pressure which is determined in the manner fully describedin-my 15 prior patent.

In the accompanying drawing, I have shown one illustrative manner ofcarrying out the present invention and in this drawing:

Figure lshows diagrammatically the manner 20 in which the method of thisinvention is carried out.

According to this invention the trace of this new foreship is obtainedin superposing on the existing construction water-line a new water- 25line, which would be obtained for the same ship in following theprocedure described in the main patent; this new waterline is thenshifted or slid forward in direction of the ships longitudinal axis, soas to bring abnortion of the new water-line in coincidence with the realwater-line of the existing ship; thus shifted, the new waterlinedetermines the contour of the new foreship.

Other advantages and particulars of the invention will be made clear indescribing the figure attached hereto. The base line A.A of this figurerepresents the longitudinal axis of a shipwhich is to be rebuiltaccording to the present invention. I is a horizontal half-section of 4the existing ship through the construction waterline plane. 2 is acorresponding horizontal half-section through the water-line plane ofthe same ship, if traced according to the procedure described in themain patent. As explained in the main patent, the frame contours of thetrace "2" are narrower than those of the trace I in the shipstransversal section which corresponds to the location of thecentre ofpressure 3, the longitudinal distance of this centre of pressure fromthe fore perpendicular as measured in meters being determined by theformula:

ship is cut oil? and replaced by a new somewhat:

elongated foreship so as to approach the contour 2r determined inshifting or sliding the contour 2" along the axis A-A" so as to bringthe centre of pressure 3' of the contour 2" in point "I" of the contour"l. to position 2'. It is to be noted that, thus shifted, a portion ofthe contour "2" comes to coincidence with the contour I (between thepoints "4 and 5'0; practically sparking only the portion 5i of'thecontour 2' remains. It is also to be noted that the elongationdetermined as above is very insignificant and increases but very littlethe ships length. Nevertheless, thanks to this elongation the samefavourable results are achieved asif the vessel were traced according tothe procedure of the invention; i. e. the resistance to forward motionisconsiderably reduced, or, otherwise speaking, the bow-wave isdiminished. The effect of elongation of the ship'sforeship according tothe above procedure is to bring the value of the angle of attack of the.ship at a certain distance from-the bowto a much smaller value of thesame angle according to the invention; this angle is reduced by adoptionof a hollower waterline so as to enable the waterstreams to flow easilypast turning rolmd the foreship and without being pushed foreward by theship's hull.

It will be noted from the drawing that the contour 2 at and forwardly ofthe point 3' is concave and when this is moved forwardly in a directionof This contour "2!" of the .new foreship is Then the contour 2 comesthe ship's longitudinal axis so as to bring a portion of the new waterline in coincidence with the real water line of the existing ship, thenew fore part of the ship-will be longitudinally concave at the waterline.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same isto be performed, I declare thatwhat Iclaim is:

The method ofmodifying the fore part of a ship's hull to increase itsspeed, which consists in making an initial waterline trace of the hullof the ship to be modified, thereupon superimposing upon the initialtrace a second waterline trace of concave form starting at the stem ofthe initial hull .trace and extending aft, thereupon -moving said secondtrace forwardly along the longitudinal center line of the hull'until thepoint -of the second trace, corresponding to the abscissa X of thecenter of pressure determined by the formula,

r V L 1 X (4r (wherein X equals the distance of the center of pressuremeasured aft along the center line of the hull from the stem thereof inmeters, V the the forward portion of the hull of the ship which conformsto the initial trace a new fore part cor-

